3,4 dihydrocoumarin and coumarin are being tested to determine chronic toxicity and carcinogenicity in B6C3F1 mice and Fischer 344/N rats and to evaluate the reversibility or progression of nonneoplastic and neoplastic lesions. These compounds were selected for testing because they are representative members of the lactone class of chemicals, a class of chemicals which have been reported to be carcinogenic. 3,4 dihydrocoumarin is used as a flavoring agent in food products; and as a fragrance in various perfumes and creams. Coumarin is used as a fixative enhancing agent for the odor of oils in perfumes; to enhance the natural taste of tobacco products, and to mask disagreeable odors in industrial products.